Adelaide schools will again be allowed to choose their stationery suppliers.

South Australian Government employees were restricted to using one supplier last year, after an investigation into printer cartridge purchases.

Public servants had received gifts in exchange for their cartridge purchases.

Newsagents were angered by the move to a sole stationery supplier, arguing jobs would be lost.

SA Finance Minister Michael O'Brien told Parliament there had been a review and the supply restriction would now be lifted on metropolitan public schools for a year.

"The extended exemption is contingent on metropolitan schools and preschools being able to demonstrate that purchase decisions are made in accordance with best-value principles," he said.

Opposition education spokesman David Pisoni said many newsagents had been affected by the buying restriction.

"We identified this as being a major problem for small business in South Australia back in October last year, when schools were first notified that they must use a single supplier," he said.

"The problem is the Government's been so slow to act, they've been ignoring the requests of small business, the concerns of small business, for the last eight or nine months and there have been redundancies."

Free trade is the oldest argument in federal politics and the issue that literally defined the federation era but opposition exists to the TPP, courtesy of the Investor-State Dispute Resolutions clause.